Well after some hours here's my first impressions:

They really just through you into it. There's no big event to start you off like in SoC, you're just dropped into the Zone to move on from there. You can start taking jobs and scouting anomalies immediately. Once you find the first base camp you'll settle into a nice routine.

The graphics are pretty good. I've got is set to DX11 with almost everything turned up to high and only get the occasional stutter which I assume is my hard drive. The water effects really stand out here. Ripples in the water and rain splashing off the barrel of your gun look the extremely realistic. That said, some of the trees and ground textures still look dated.
The sky is amazing looking. The night pitch freaking black. Seriously it's damn dark. It's half the reason I choose to just sleep at night. Yeah you read that right. You've got to eat and sleep if you want to live.

The atmosphere you've come to know in the Stalker series is still there and thriving. Just going out into the zone is a test of will with mutants, zombies, and emissions to contend with.

Emissions happen regularly now, usually in the mornings and send everyone NPC's included running for cover. Sometimes it can work in your favor as I rode out the first emission I stepped outside to find 2 dead stalkers right outside the door. While tragic for them I decided to carry on their names, by carrying away all their belongings.

I'm pretty happy with the purchase. Just one more thing to keep me from getting the nerve to get ArmA 2 up and running again.